1. Field of the Invention
The present invention relates to a concealed type slide fastener having a fastener stringer in which opposing side edges of a pair of right and left fastener tapes are bent into a U shape along a length direction thereof while a plurality of fastener elements are attached along the bent side edges. More particularly, the invention relates to a concealed type slide fastener having a feature in a structure of a separable end stop comprising a box pin and an insert pin formed of a thermoplastic synthetic resin and integrally formed with each end portion in a length direction of the pair of fastener stringers and a box integrated with the box pin so that the insert pin can be inserted into and removed from the box.
2. Description of Related Art
In an ordinary slide fastener, a pair of fastener stringers configured such that a plurality of fastener elements are attached along opposing side edges of a pair of right and left fastener tapes are made to pass through a slider, and the slide fastener is opened or closed by engaging the right and left fastener elements or releasing the engagement by the sliding operation of the slider. To define the sliding limit of the slider, end stops are formed at both end portions in the length direction of the slide fastener.
To the contrary, in a concealed type slide fastener, opposing side edges of a pair of right and left fastener tapes are bent into a U shape in cross section along a length direction thereof. With the shape fixed, a plurality of fastener elements are attached along an outside face of the U-shaped folded portion at a predetermined pitch, thereby forming fastener stringers. End stops are formed on both end portions in the length direction of the fastener stringer like the ordinary slide fastener.
Ordinary end stops include a top end stop which always keeps end portions of the right and left fastener stringers in a separated state and a bottom end stop which always keep the end portions of the right and left fastener stringers in a coupled state. The separable end stop is a kind of the bottom end stop. When an insert pin is removed from a box and pulled out of a slider also in order to release the slide fastener, the right and left fastener stringers can be completely separated from each other. When the insert pin is inserted into the box through the slider, the right and left fastener stringers are joined together through the box pin and box. By sliding the slider, opposing fastener elements of the separated right and left fastener stringers are engaged together to close the slide fastener.
The separable end stop of the concealed type slide fastener has a peculiar structure different form the separable end stop of the ordinary slide fastener. This originates from the tape folding structure of the fastener stringer in the concealed type slide fastener and the slider structure suitable for the folding structure. The slider of the concealed type slide fastener has no upper blade which is exposed on the surface of a product, but has right and left flanges L shaped in cross section. The flanges L rise toward the front surface of the product from right and left ends of a lower blade disposed on the rear side of the product so that the flanges are bent at right angle in directions in which they approach each other. The slider further includes a post rising toward the front surface of the product from the center of one end portion of the lower blade and having a pull tab attaching portion at a front end thereof. A Y-shaped space formed between the lower blade and the flange having the L-shaped section serves as an element guide passage.
When the slider of the concealed type slide fastener is slid, fastener element rows are guided into the Y-shaped element guide passage in the slider and need to be introduced with the tape main body side of the U-shaped folded portion of the fastener tape extracted out from a gap between the flange of the slider and the post. More specifically, when coupling the separable end stop, an insert pin attached to the end portion of one fastener stringer needs to be made to pass through the space portion formed between the flange having the L-shaped section of the slider and the lower blade, and then inserted into an insert pin insertion space of a box attached to the end portion of the other fastener stringer. At this time, the insert pin is easy to insert if constituted of a single rod-like body. However, when a force (lateral pulling force) in a direction crossing the element row of the slide fastener is applied to the fastener tape, the insert pin is apt to roll inside the box as described in, for example, Japanese Patent Application Laid-Open (JP-A) No. 2003-180411 (patent document 1).
The separable end stop according to the patent document 1 is constituted of two components, a box insertion/removal portion which is inserted into the insert pin insertion space of the box in order to block the insert pin from rolling inside the box when a lateral pulling force is applied, and an engaging/disengaging portion which is engaged with or disengaged from the box insertion/removal portion across the flange of the slider. On the other hand, a wall portion is formed on the box between the insert pin insertion space in which the box insertion/removal portion of the insert pin is to be inserted and the engaging/disengaging portion with which the engaging/disengaging portion engages. Consequently, the box insertion/removal portion and the engaging/disengaging portion are separated such that the wall portion is sandwiched between the box insertion/removal portion and the engaging/disengaging portion when the box insertion/removal portion of the insert pin is inserted into the insert pin insertion space. In addition, lateral grid-like reinforcing portions are formed integrally on the surface of the tapes opposite to the element attaching side, continuous from the insert pin and the box pin at the same time. With such a structure, even if a lateral pulling force is applied to the slide fastener after the insert pin is inserted into the box, such a fault that the insert pin rolls inside the box is eliminated.
In the concealed type slide fastener described in the patent document 1, the insert pin is inserted into the box such that the box insertion/removal portion and engaging/disengaging portion of the insert pin stride over the wall portion of the box, and consequently, the insert pin is never rolled by the lateral pulling force described above.
In the concealed type slide fastener described in the patent document 1, however, the box insertion/removal portion and the engaging/disengaging portion are completely separated from each other. For this reason, when the box insertion/removal portion is inserted through the space formed between the lower blade of the slider and the flange having a L-shaped section, the lower blade of the slider is likely to be caught between the box insertion/removal portion and the engaging/disengaging portion by mistake, with the result that if an attempt is made to push the portion strongly, a branch portion between the box insertion/removal portion and the engaging/disengaging portion can be broken as if it is torn out. When the insert pin is attempted to be inserted into the insert pin insertion space of the box, the engaging/disengaging portion is caught by the wall portion of the box. As a result, the engaging/disengaging portion cannot be inserted smoothly up to an engaged/disengaged portion of the box and further, if an attempt is made to push the portion forcibly, the engaging/disengaging portion can be broken.
Further, the box insertion/removal portion and the engaging/disengaging portion of the insert pin are completely separated from a base portion. Therefore, for example, when a strong upward pushing force is applied, the engaging/disengaging portion is deformed elastically and slips out of the box, whereby the coupling state between the right and left fastener stringers is likely released to separate the right and left fastener stringers.